This proposal seeks support to establish the infrastructure for a Breast Cancer Research Program at the University of Southern California (USC)/Norris Comprehensive Cancer Center (NCCC). The NCCC has a long history of breast cancer research, especially in the areas of epidemiology and prevention, but has never had a formal focussed interdisciplinary research program devoted to breast cancer. The proposed program seeks to take advantage of the extraordinary racial- ethnic diversity among the 9 million residents of Los Angeles County, the population served by the NCCC. Our goal is to better understand the reasons for the underlying differences in breast cancer incidence, mortality and survival among the numerically most important of these racial-ethnic groups in the County (African-Americans, Latinas, Japanese, Chinese, Filipinas, Koreans and non-Latina whites). We perceive a multifaceted approach involving epidemiology and prevention scientists, behavioral scientists, tumor biologists and molecular geneticists, and radiation, surgical and medical oncologists. We will take advantage of numerous patient and data resources available to us to achieve this goal. These include the Los Angeles County SEER cancer registry program; a large registry of breast cancer in twins; dietary and lifestyle data from recently characterized large racial-ethnically diverse cohorts; a large and diverse clinical population seen at NCCC affiliated hospitals; and several large tumor and other biological sample banks for studies of tumor biology and molecular genetics. We describe and document in this application the commitment of the NCCC and our parent organization, the USC School of Medicine, to establish this Program; we give examples of and describe the evaluation process for funding pilot research projects; we describe our Program recruitment priorities; and we overview the planned organizational structure of the Program relative to the NCCC overall, and with regards to internal and external advisory groups and their functions.